Compilation errors when writing a quadratic formula program

One of the constructors you've defined is

QuadEquation::QuadEquation()
{
  int a,b,c;
}

But this constructor isn't defined in your header file. Moreover, it looks like this is an error on your part, since this constructor doesn't make much sense - it just declares three local variables and doesn't use any of them. If you do want to declare this constructor, add it to your header file, but judging from your code I don't believe it's necessary.

As to your other errors, look at this code:

int QuadEquation::getRoot1()
{
  discrim = getDiscrimant();
  return -b + sqrt(discrim) / (2 * a);
}

Two things jump out at me. First, where is discrim declared? Second, if quadratic formulas can have arbitrary complex-valued roots, is there a reason you're returning an int? Is there a different type you could use here instead?

Overall, you should learn to read these compiler error messages. Everything I've pointed out could easily have been gleaned from the error output. Now that you're aware what the problems are, can you see how they generate the given compiler errors?

Hope this helps!